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Biosens Bioelectron. 2011 Apr 15;26(8):3577-83. doi: 10.1016/j.bios.2011.02.004. Epub 2011 Feb 15.

Ternary monolayers as DNA recognition interfaces for direct and sensitive electrochemical detection in untreated clinical samples.

Author information

1
Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA.

Abstract

Detection of specific DNA sequences in clinical samples is a key goal of studies on DNA biosensors and gene chips. Herein we present a highly sensitive electrochemical genosensor for direct measurements of specific DNA sequences in undiluted and untreated human serum and urine samples. Such genosensing relies on a new ternary interface involving hexanedithiol (HDT) co-immobilized with the thiolated capture probe (SHCP) on gold surfaces, followed by the incorporation of 6-mercapto-1-hexanol (MCH) as diluent. The performance of ternary monolayers prepared with linear dithiols of different lengths was systematically examined, compared and characterized by cyclic voltammetry and electrochemical impedance spectroscopy, with HDT exhibiting the most favorable analytical performance. The new SHCP/HDT+MCH monolayer led to a 80-fold improvement in the signal-to-noise ratio (S/N) for 1 nM target DNA in undiluted human serum over the common SHCP+MCH binary alkanethiol interface, and allowed the direct quantification of the target DNA down to 7 pM (28 amol) and 17 pM (68 amol) in undiluted/untreated serum and urine, respectively. It also displayed attractive antifouling properties, as indicated from the favorable S/N obtained after a prolonged exposure (24h) to untreated biological matrices. These attractive features of the SHCP/HDT+MCH sensor interface indicate considerable promise for a wide range of clinical applications.

PMID:
21377347
PMCID:
PMC3065524
DOI:
10.1016/j.bios.2011.02.004
[Indexed for MEDLINE]
Free PMC Article

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