Biosensors and Bioelectronics 26 (2011) 4213–4216 Contents lists available at ScienceDirect Biosensors and Bioelectronics journal homepage: www.elsevier.com/locate/bios Short communication A graphene-based platform for single nucleotide polymorphism (SNP) genotyping Meng Liu, Huimin Zhao ∗ , Shuo Chen, Hongtao Yu, Yaobin Zhang, Xie Quan Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China article info Article history: Received 11 January 2011 Received in revised form 20 March 2011 Accepted 27 March 2011 Available online 1 April 2011 Keywords: Adsorption DNA ligase Fluorescence Graphene Single nucleotide polymorphism (SNP) abstract A facile, rapid, stable and sensitive approach for fluorescent detection of single nucleotide polymorphism (SNP) is designed based on DNA ligase reaction and -stacking between the graphene and the nucleotide bases. In the presence of perfectly matched DNA, DNA ligase can catalyze the linkage of fluorescein amidite-labeled single-stranded DNA (ssDNA) and a phosphorylated ssDNA, and thus the formation of a stable duplex in high yield. However, the catalytic reaction cannot effectively carry out with one- base mismatched DNA target. In this case, we add graphene to the system in order to produce different quenching signals due to its different adsorption affinity for ssDNA and double-stranded DNA. Taking advantage of the unique surface property of graphene and the high discriminability of DNA ligase, the proposed protocol exhibits good performance in SNP genotyping. The results indicate that it is possible to accurately determine SNP with frequency as low as 2.6% within 40 min. Furthermore, the presented flexible strategy facilitates the development of other biosensing applications in the future. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Single nucleotide polymorphism (SNP) represents one of the most frequent and stable form of genetic variations in human genomic DNA. With the development of genetic therapy, clinical diagnosis and molecular biology, SNP is regarded as not only a genetic marker in the study of cancer-related drug metabolism or reactivity, but also a fundamental tool in the identification of inherited disease-causing genes (Imyanitov et al., 2004; McCarthy and Hilfiker, 2000; Sidransky, 2002; Sauna, 2007). Therefore, great efforts have been devoted to developing technique methods for screening SNP, such as allele specific oligonucleotide hybridiza- tion (Ding et al., 2010; Liu et al., 2005; Liu and Lin, 2007), endonuclease digestion (Gaylord et al., 2005; Li and Liu, 2009), primer extension (Duan et al., 2009a; Litos et al., 2009; Nelson et al., 1996), oligonucleotide ligation (Huh et al., 2009; Li et al., 2006; Lowe et al., 2010; Xue et al., 2009), nonenzymatic ligation (Xu et al., 2001), DNA-specific redox indicators and conjugated mediators (Drummond et al., 2003; Kelley et al., 1999), in com- bination with fluorescence (FL) (Duan et al., 2007; Guo et al., 2010; Liu et al., 2009; Wang and Liu, 2007), electrochemistry (Kerman et al., 2004; Zhang et al., 2008), chemiluminescence (Liu et al., 2006), colorimetry (He et al., 2010a,b; Lee et al., 2010), ∗ Corresponding author. Tel.: +86 411 84706263; fax: +86 411 84706263. E-mail address: zhaohuim@dlut.edu.cn (H. Zhao). and mass spectrometry (Mattes and Seitz, 2001) as signal read- out. In particular, FL-based homogeneous assays relied on donor- acceptor pair, TaqMan or DNA enzyme have attracted considerable interest in the study of SNP. Among these, various platforms includ- ing molecular beacons (MBs) (Tyagi and Kramer, 1996; Xiao et al., 2009), conjugated polymers (CPs) (Duan et al., 2009b), and Au nanoparticles (NPs) (Wang et al., 2010) make significant achieve- ments in allowing high-throughput SNP identification through energy or electron transfer mechanism. For example, MBs-based strategy enables high specific, accurate and selective detection of SNP without the need for multiple separation steps. However, the development of MBs-based probes inevitably require expen- sive and complicated dual-labeled primers, resulting in a high FL background, thus limiting the detection sensitivity (Zheleznaya et al., 2006). Another design strategy utilizing CPs as optical trans- ducer provides a facile, rapid and homogeneous platform for SNP identification. Due to the electrostatic interaction between DNA and cationic CPs, it can be concluded that CPs-based probes are extremely sensitive to the environmental conditions (pH, ionic strength and precursor concentration) according to classical Derjaguin–Landau–Verwey–Overbeek theory (Zhang and Wang, 2008), which will ultimately bring false positive results. Addi- tional efforts of Au NPs-based platforms allow effective long-range FL quenching over a broad range of wavelength (Lennings et al., 2006; Singh and Strouse, 2010; Yun et al., 2005), thus establish- ing a universally applicable method that offer highly sensitive 0956-5663/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2011.03.023