title: Electrochemical impedance behavior of DNA biosensor based on colloidal Ag and bilayer two-dimensional sol-gel as matrices.
abstract: A novel method for fabrication of DNA biosensors has been developed by means of self-assembling colloidal Ag (Ag) to a thiol-containing sol-gel network. The thiol groups of 3-mercaptopropyltrimethoxysilane (MPTS) serve as binding sites for the covalent attachment to gold electrode surface. Then the one-dimensional network of silane unites (1dMPTS) was combined together into a two-dimensional sol-gel network (2dMPTS) by dipping into aqueous NaOH. The second silane layer (B2dMPTS) was formed by immersing electrodes back into the MPTS solution overnight, and then the Ag nanoparticles were chemisorbed onto the thiol groups of the second silane layer. Finally, the mercapto oligonucleotide was self-assembled onto the surface via the Ag nanoparticles. The modified process was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). In addition, we utilized the impedance spectroscopy as a platform for DNA sensing assay. The factors influencing the performance of the resulting biosensor were studied in detail. The linear range of the biosensor was from 8.0 x 10(-9) to 1.0 x 10(-6) M with a detection limit of 4.0 x 10(-9) M at 3sigma. In addition, the experiment results indicate that oligonucleotide immobilized on this way exhibits a good sensitivity and selectivity, high stability and a long-term maintenance of bioactivity.
authors.affiliation: Chongqing Key Laboratory of Analytical Chemistry, College of Chemistry and Chemical Engineering, Southwest China Normal University, Chongqing 400700, PR China.
authors.forename: Yingzi
authors.initials: Y
authors.lastname: Fu
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
authors.forename: Lan
authors.initials: L
authors.lastname: Xu
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D001665:Binding Sites; D015374:Biosensing Techniques; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D017097:Electric Impedance; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D008956:Models, Chemical; D009693:Nucleic Acid Hybridization; D009841:Oligonucleotides / Q000737:chemistry; D017646:Organosilicon Compounds; D044367:Phase Transition; D012680:Sensitivity and Specificity; D012821:Silanes / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D009841:Oligonucleotides; D017646:Organosilicon Compounds; D012821:Silanes; D012834:Silver; D012972:Sodium Hydroxide; C102833:(3-mercaptopropyl)trimethoxysilane; D004247:DNA