title: Sensitive detection of unlabeled oligonucleotides using a paired surface plasma waves biosensor.
abstract: Detection of unlabeled oligonucleotides using surface plasmon resonance (SPR) is difficult because of the oligonucleotides' relatively lower molecular weight compared with proteins. In this paper, we describe a method for detecting unlabeled oligonucleotides at low concentration using a paired surface plasma waves biosensor (PSPWB). The biosensor uses a sensor chip with an immobilized probe to detect a target oligonucleotide via sequence-specific hybridization. PSPWB measures the demodulated amplitude of the heterodyne signal in real time. In the meantime, the ratio of the amplitudes between the detected output signal and reference can reduce the excess noise from the laser intensity fluctuation. Also, the common-path propagation of p and s waves cancels the common phase noise induced by temperature variation. Thus, a high signal-to-noise ratio (SNR) of the heterodyne signal is detected. The sequence specificity of oligonucleotide hybridization ensures that the platform is precisely discriminating between target and non-target oligonucleotides. Under optimized experimental conditions, the detected heterodyne signal increases linearly with the logarithm of the concentration of target oligonucleotide over the range 0.5-500 pM. The detection limit is 0.5 pM in this experiment. In addition, the non-target oligonucleotide at concentrations of 10 pM and 10nM generated signals only slightly higher than background, indicating the high selectivity and specificity of this method. Different length of perfectly matched oligonucleotide targets at 10-mer, 15-mer and 20-mer were identified at the concentration of 150 pM.
authors.affiliation: Department of Optics and Photonics, National Central University, Taoyuan, 320, Taiwan; Graduate Institute of Electro-Optical Engineering, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Ying-Chang
authors.initials: YC
authors.lastname: Li
authors.affiliation: Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Chiuan-Chian
authors.initials: CC
authors.lastname: Chiou
authors.affiliation: Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Ji-Dung
authors.initials: JD
authors.lastname: Luo
authors.affiliation: Graduate Institute of Electro-Optical Engineering, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Wei-Ju
authors.initials: WJ
authors.lastname: Chen
authors.affiliation: Department of Optics and Photonics, National Central University, Taoyuan, 320, Taiwan; Graduate Institute of Electro-Optical Engineering, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Li-Chen
authors.initials: LC
authors.lastname: Su
authors.affiliation: Graduate Institute of Electro-Optical Engineering, Chang Gung University, Taoyuan, 333, Taiwan; Molecular Medicine Research Center, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Ying-Feng
authors.initials: YF
authors.lastname: Chang
authors.affiliation: Molecular Medicine Research Center, Chang Gung University, Taoyuan, 333, Taiwan; Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Yu-Sun
authors.initials: YS
authors.lastname: Chang
authors.affiliation: Department of Electronic Engineering, Chang Gung University, Taoyuan, 333, Taiwan; Biomedical Engineering Research Center, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: Chao-Sung
authors.initials: CS
authors.lastname: Lai
authors.affiliation: Department of Optics and Photonics, National Central University, Taoyuan, 320, Taiwan.
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Department of Optics and Photonics, National Central University, Taoyuan, 320, Taiwan; Graduate Institute of Electro-Optical Engineering, Chang Gung University, Taoyuan, 333, Taiwan; Biomedical Engineering Research Center, Chang Gung University, Taoyuan, 333, Taiwan. Electronic address: cchou@mail.cgu.edu.tw.
authors.forename: Chien
authors.initials: C
authors.lastname: Chou
mesh_terms: D001483:Base Sequence; D057230:Limit of Detection; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes / Q000235:genetics; D009841:Oligonucleotides / Q000032:analysis* / Q000235:genetics; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D020349:Surface Plasmon Resonance / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D015345:Oligonucleotide Probes; D009841:Oligonucleotides