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Issue 7, 2018
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Actuation of chitosan-aptamer nanobrush borders for pathogen sensing

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We demonstrate a sensing mechanism for rapid detection of Listeria monocytogenes in food samples using the actuation of chitosan-aptamer nanobrush borders. The bio-inspired soft material and sensing strategy mimic natural symbiotic systems, where low levels of bacteria are selectively captured from complex matrices. To engineer this biomimetic system, we first develop reduced graphene oxide/nanoplatinum (rGO-nPt) electrodes, and characterize the fundamental electrochemical behavior in the presence and absence of chitosan nanobrushes during actuation (pH-stimulated osmotic swelling). We then characterize the electrochemical behavior of the nanobrush when receptors (antibodies or DNA aptamers) are conjugated to the surface. Finally, we test various techniques to determine the most efficient capture strategy based on nanobrush actuation, and then apply the biosensors in a food product. Maximum cell capture occurs when aptamers conjugated to the nanobrush bind cells in the extended conformation (pH < 6), followed by impedance measurement in the collapsed nanobrush conformation (pH > 6). The aptamer-nanobrush hybrid material was more efficient than the antibody-nanobrush material, which was likely due to the relatively high adsorption capacity for aptamers. The biomimetic material was used to develop a rapid test (17 min) for selectively detecting L. monocytogenes at concentrations ranging from 9 to 107 CFU mL−1 with no pre-concentration, and in the presence of other Gram-positive cells (Listeria innocua and Staphylococcus aureus). Use of this bio-inspired material is among the most efficient for L. monocytogenes sensing to date, and does not require sample pretreatment, making nanobrush borders a promising new material for rapid pathogen detection in food.

Graphical abstract: Actuation of chitosan-aptamer nanobrush borders for pathogen sensing

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Publication details

The article was received on 18 Dec 2017, accepted on 07 Mar 2018 and first published on 08 Mar 2018

Article type: Paper
DOI: 10.1039/C7AN02039B
Citation: Analyst, 2018,143, 1650-1661
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    Actuation of chitosan-aptamer nanobrush borders for pathogen sensing

    K. D. Hills, D. A. Oliveira, N. D. Cavallaro, C. L. Gomes and E. S. McLamore, Analyst, 2018, 143, 1650
    DOI: 10.1039/C7AN02039B

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