G-quadruplex based impedimetric 2-hydroxyfluorene biosensor using hemin as a peroxidase enzyme mimic

Abstract

We describe a sensitive and selective biosensor for the environmental metabolite 2-hydroxyfluorene (2-HOFlu). It is based on electrochemical impedance spectroscopy and was obtained by assembling a thiolated single-stranded DNA on a gold electrode via S-Au covalent bonding. It is then transformed to a K + -stabilized G-quadruplex-hemin complex which exhibits peroxidase-like activity to catalyze the oxidation of 2-HOFlu by H 2 O 2 . This results in the formation of insoluble products that are precipitated on the gold electrode. As a result, the charge transfer resistance (R CT ) between the solution and the electrode surface is strongly increased within 10 min as demonstrated by using the ferro/ferricyanide system as a redox probe. The difference in the charge transfer resistances (ΔR CT ) before and after incubation of the DNA film with 2-HOFlu and H 2 O 2 serves as the signal for the quantitation of 2-HOFlu with a 1.2. nM detection limit in water of pH 7.4. The assay is highly selective over other selected fluorene derivatives. It was exploited to determine 2-HOFlu in spiked lake water samples where it displayed a detection limit of 3.6 nM. Conceivably, this method has a wide scope in that it may be applied to other analytes for which respective G-quadruplexes are available.

Aptamer-based biosensor for label-free detection of ethanolamine by electrochemical impedance spectroscopy

“…And electrochemical impedance spectroscopy (EIS) has been proven to be a most powerful and sensitive tool for probing the features of surface-modified electrodes [18]. EIS biosensors possess unique advantages, such as the ability to separate the surface binding events from the solution impedance, ease of signal quantification, less damage to the biological interactions being measured, and the possibility to use non-labeled DNA [19].…”

“…The gold electrodes were cleaned prior to thiolated DNA modification as reported before [19]. Briefly,the gold electrodes were first mechanically polished on a microcloth (Buehler) with …”

Electrochemical and AFM Characterization of G-Quadruplex Electrochemical Biosensors and Applications

“…A hemin/G4 DNAzyme based impedimetric biosensor was used to detect the environmental metabolite 2-hydroxyfluorene (2-HOFlu) [ 87 ]. Using the hemin/G4 peroxidase activity to catalyze the oxidation of 2-HOFlu by H 2 O 2 , the sensor achieved a 2-HOFlu detection limit of 1.2 nM in water and 3.6 nM in spiked lake water samples.…”

Guanine Quadruplex Electrochemical Aptasensors

“…In comparison with protein peroxidases, the hemin/G4 peroxidase-mimicking DNAzymes have several advantages, such as high chemical stability, low cost and simple synthesis. Hemin/G4 DNAzyme electrochemical biosensors were successfully used for the detection of cells [106,107], proteins [108][109][110] or low molecular weight molecules, such as adenosine monophosphate (AMP) [102,111,112], anticancer drugs [113], gaseous ligands [114], toxins [115,116], pollutant agents [117,118] or metal ions [119,120].…”

“…A hemin/G4 DNAzyme-based impedimetric biosensor was used to detect the environmental metabolite 2-hydroxyfluorene (2-HOFlu) [117], using the hemin/G4 HRP-like activity to catalyze the oxidation of 2-HOFlu by H 2 O 2 , with a 1.2 nM detection limit in water and a 3.6 nM detection limit in spiked lake water samples. The assay was also selective over other fluorene derivatives.…”