0013-4651/2015/162(12)/B291/7/$33.00 © The Electrochemical Society A Sensitive DNA Biosensor Using Graphene Oxide as the Multi-Site Platform for Probe DNA Immobilization

An ultrasensitive DNA biosensor was constructed in this work by using graphene oxide nanosheets (GONs) as the multi-site platform for probe DNA immobilization. First, L-cysteine (L-cys) was self-assembled on a gold electrode surface based on the Au-S chemistry. Then the GONs and amino modified probe DNA was covalently grafted to L-cys/AuE surface in turn, with the aid of 1-(3-Dimethylanminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-Hydroxy succinimide (NHS). The layer upon layer assembly process was characterized with atomic force microscopy and electrochemical methods. Due to the nano-size effect and multiple site characteristic of GONs, the immobilization density of the probe DNA was determined to be as high as 5.72 × 10−10 mol cm−2 using methylene blue as the redox probe. The hybridization experiments showed that the biosensor can quantitatively detect target DNA in a wide range from 1.0 × 10−15 M to 1.0 × 10−9 M with a detection limit of 5.0 × 10−16 M. The selectivity experiments showed that the sensing system could accurately discriminate the complementary sequence from the base mismatched and non-complementary sequences. © 2015 The Electrochemical Society. [DOI: 10.1149/2.0011512jes] All rights reserved. Manuscript submitted February 3, 2015; revised manuscript received July 6, 2015. Published August 20, 2015. With the development of biotechnology, simple, fast and sensitive detection of DNA provides promising potential in forensic, clinical and pharmaceutical applications.1 So far, various techniques hav