Functionalized nanocomposites with the optimal graphene oxide/Au ratio for amplified immunoassay of E. coli to estimate quality deterioration in dairy product.
An amplified electrochemical immunosensor was developed by exploiting poly(diallyldimethylammonium chloride)-functionalized graphene oxide and gold nanoparticles (GO-PDDA@AuNP) as sensing platform. Highlight of this work was to investigate and optimize the ratio of GO-PDDA to AuNP for sensitivity enhancement. The suitable GO-PDDA@AuNP nanocomposites were proven to not only provide an excellent biocompatible microenvironment for the immobilized antibody, but also accelerate electron transfer to enhance electrochemical signal. Moreover, the {dAb-Au-THi} nanoprobes as biorecognition elements were designed by utilizing the amplification effect of AuNPs to load detection antibody (dAb) and enormous thionine (THi), in whichdAb was used for specific recognition of E. coli and THi served as electroactive species. Under optimal conditions, experimental results demonstrated that the variations (ΔI) in the peak current linearly depended on the logarithmic value of E. coli concentration from 50 to 5.0×106cfumL-1with the detection limit of 35cfumL-1. Recovery experiments were also performed for E. coli assay in dairy product (pure fresh milk, yogurt in shelf-life and expired yogurt), and the recoveries of standard additions were in the range of 89.7-112.6%. The excellent performance of the proposed strategy indicated its promising prospect as a valuable tool to estimate the quality deterioration in dairy product.
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China. Electronic address: zhangxinai@mail.ujs.edu.cn.
Xinai
X
Zhang
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
Yuxiang
Y
Jiang
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
Chenyong
C
Huang
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
Jianzhong
J
Shen
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
Xiaoya
X
Dong
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
Guangwei
G
Chen
Department of Chemistry, East China Normal University, Shanghai 200062, PR China.
Wen
W
Zhang
D000818:Animals; D000906:Antibodies / Q000737:chemistry*; D015374:Biosensing Techniques; D004926:Escherichia coli / Q000302:isolation & purification* / Q000472:pathogenicity; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D008892:Milk / Q000382:microbiology; D010087:Oxides / Q000737:chemistry; D010640:Phenothiazines / Q000737:chemistry; D011095:Polyethylenes / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D015014:Yogurt / Q000382:microbiology
D000906:Antibodies; D010087:Oxides; D010640:Phenothiazines; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D006046:Gold; D006108:Graphite; C009469:thionine
Dairy product; E. coli; Electrochemical immunosensing; Functionalized graphene oxide; Signal amplification