A comparison of four protocols for the immobilization of an aptamer on graphite composite electrodes
Ocaña Tejada, Cristina (Universitat Autònoma de Barcelona. Departament de Química)
Valle Zafra, Manuel del (Universitat Autònoma de Barcelona. Departament de Química)

Date:	2014
Abstract:	We have performed a comparative study on four protocols for the immobilization of the thrombin aptamer on a graphite-epoxy composite electrode with the aim to identify the most practical method for designing the corresponding impedimetric aptasensor. The protocols included (a) physical adsorption, (b) avidin-biotin affinity interaction, (c) electrochemical activation and covalent bonding via amide groups, and (d) electrochemical grafting using 4-carboxybenzenediazonium coupling. The properties of the sensing surface were probed by electrochemical impedance measurements in the presence of the (ferri/ferro)hexacyanide redox couple. An increase in the interfacial charge transfer resistance (Rct) was noted in all cases after the aptamer-thrombin interaction had occurred. The selectivity of the aptasensor over common serum proteins was also systematically investigated. Physical adsorption resulted in the lowest detection limit of the probe (4. 5 pM), while avidin-biotin interaction resulted in highest selectivity and reproducibility exhibiting a 4. 9 % relative standard deviation at pM thrombin concentration levels.
Grants:	Ministerio de Ciencia e Innovación CTQ2010-17099
Note:	Altres ajuts: ICREA Academia
Rights:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Aptamer ; Electrochemical impedance spectroscopy ; Immobilization ; Label-free ; Thrombin
Published in:	Mikrochimica acta, Vol. 181, Issue 3-4 (February 2014) , p. 355-363, ISSN 1436-5073

DOI: 10.1007/s00604-013-1126-0

Postprint 22 p, 457.6 KB

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