title: Polymeric membrane neutral phenol-sensitive electrodes for potentiometric G-quadruplex/hemin DNAzyme-based biosensing.
abstract: The first potentiometric transducer for G-quadruplex/hemin DNAzyme-based biosensing has been developed by using potential responses of electrically neutral oligomeric phenols on polymeric membrane electrodes. In the presence of G-quadruplex/hemin DNAzyme and H(2)O(2), monomeric phenols (e.g., phenol, methylphenols, and methoxyphenols) can be condensed into oligomeric phenols. Because both substrates and products are nonionic under optimal pH conditions, these reactions are traditionally not considered in designing potentiometric biosensing schemes. However, in this paper, the electrically neutral oligomeric phenols have been found to induce highly sensitive potential responses on quaternary ammonium salt-doped polymeric membrane electrodes owing to their high lipophilicities. In contrast, the potential responses to monomeric phenolic substrates are rather low. Thus, the G-quadruplex/hemin DNAzyme-catalyzed oxidative coupling of monomeric phenols can induce large potential signals, and the catalytic activities of DNAzymes can be probed. A comparison of potential responses induced by peroxidations of 13 monomeric phenols indicates that p-methoxyphenol is the most efficient substrate for potentiometric detection of G-quadruplex/hemin DNAzymes. Finally, two label-free and separation-free potentiometric DNA assay protocols based on the G-quadruplex/hemin DNAzyme have been developed with sensitivities higher than those of colorimetric and fluorometric methods. Coupled with other features such as reliable instrumentation, low cost, ease of miniaturization, and resistance to color and turbid interferences, the proposed polymeric membrane-based potentiometric sensor promises to be a competitive transducer for peroxidase-mimicking DNAzyme-involved biosensing.
authors.affiliation: Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai 264003, PR China.
authors.forename: Xuewei
authors.initials: X
authors.lastname: Wang
authors.forename: Zhaofeng
authors.initials: Z
authors.lastname: Ding
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Ren
authors.forename: Wei
authors.initials: W
authors.lastname: Qin
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D021881:DNA, Catalytic / Q000032:analysis / Q000737:chemistry*; D004566:Electrodes; D054856:G-Quadruplexes; D006427:Hemin / Q000032:analysis / Q000737:chemistry*; D019800:Phenol / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods
chemical_list: D021881:DNA, Catalytic; D011108:Polymers; D019800:Phenol; D006427:Hemin