Journal
BIOSENSORS & BIOELECTRONICS
Volume 126, Issue -, Pages 493-500Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2018.11.001
Keywords
Metal-organic frameworks; CdS quantum dot; Immunobiosensor; Escherichia coli O157:117; Zeolitic imidazolate framework-8
Categories
Funding
- National Natural Science Foundation of China [21705045, 21305041, 21475041]
- Science and Technology Innovation Project of Hunan Province [2018RS3062]
- Natural Science Foundation of Hunan Province [2018JJ2252]
- Scientific Research Fund of Hunan Provincial Education Department [17A125]
- Science and Technology Project of Changsha [KQ1707009]
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We report here cadmium sulfide quantum dots (CdS QDs)-encapsulated metal-organic frameworks as signal-amplifying tags for ultrasensitive electrochemical detection of Escherichia coli O157:H7 (E. coli O157:H7). CdS QDs were encapsulated in zeolitic imidazolate framework-8 (ZIF-8) to form CdS@ZIF-8 muti-core-shell particles by in situ growth of ZIF-8 in the presence of CdS QDs. To specifically recognize E. coli O157:H7 cells, CdS@ZIF-8 particles were coated with polyethyleneimine to introduce amino groups on their surfaces, followed by surface modification of anti-E. coli O157:H7 antibody. A sandwich-type electrochemical immunobiosensor for the detection of E. coli O157:H7 was fabricated using CdS@ZIF-8 particles as signal tags. Cd(II) ions were released from CdS@ZIF-8 tags by HCl leaching, enabling the detection of E. coli O157:H7 by differential pulse voltammetry. Under the optimized conditions, the linear range of the biosensor is from 10 to 10(8) colony forming units (CFU) per mL for E. coli O157:H7 detection, with the detection limit of 3 CFU mL(-1) (S/N = 3). The sensitivity of the biosensor for E. coli O157:H7 detection using CdS@ZIF-8 particles as signal tags is 16 times that of a biosensor using CdS QDs as signal tags, because the number of CdS QDs labeled to each bacterial cell increases greatly resulting from a great number of CdS QDs encapsulated in each CdS@ZIF-8 label. This method was successfully used to detect E. coli O157:H7 in milk samples.
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