Polymeric Membrane Neutral Phenol-Sensitive Electrodes for Potentiometric G-Quadruplex/Hemin DNAzyme-Based Biosensing

Abstract

ABSTRACT:The first potentiometric transducer for Gquadruplex/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. C atalytic DNA molecules (DNAzymes) have found wide use in biosensing, biotechnology, and logic gate applications with advantages of simple preparation, easy modification, low cost, and high thermal stability.

Quantitative determination of fucoidan using polyion-sensitive membrane electrodes

“…This result is expected since the two samples have similar peak molecular weights and wt.% sulfate, and indicates that polyphenols and other components often found in nutritional grade extracts from macroalgae do not affect sensor performance (one would expect polyphenols to be neutral at pH 7.4). Wang et al recently reported that TDMA-doped polymeric membrane electrodes were capable of responding to neutral phenols [49]. However, the minimum detection limit for polyphenols in that work was much higher than the polyphenol concentration in any of the fucoidan preparations studied here (all fucoidan preparations contained <2 m/m% polyphenol).…”

A potentiometric biosensing system based on an isolated degrading bacterium Klebsiella sp. MP-6 for the determination of methyl parathion

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An all-solid-state imprinted polymer-based potentiometric sensor for determination of bisphenol S

“…These unexpected anionic responses can be explained by the net movement of hydrogen ions from the membrane phase to the aqueous phase 70 stimulated by neutral phenols. 28,32,33 Inspired by these findings, we explored the application of the nonclassical response in the BPS determination. In order to guarantee that BPS exists mostly in its neutral form, 30 mM phosphate buffer solution (PBS) with a pH of 5.0 was used as the background solution.…”