An ultrasensitive and label-free electrochemical DNA biosensor for detection of DNase I activity

Abstract

An ultrasensitive and label-free DNA biosensor for the detection of deoxyribonuclease I (DNase I) activity was comprehensively studied based on electrochemical methods by cyclic voltammetry (CV) and square wave voltammetry (SWV). For the preparation of the DNA biosensor, the arbitrary 76-bp single-stranded DNA reporter probes and electrochemical indicator methylene blue (MB) were modified on the Au electrode. Initially, the sensor generated a strong signal because of the redox indicator MB. In the presence of DNase I, the enzyme cleaved single-stranded DNA at their phosphate backbone, and then the MB was removed from the electrode, resulting in the reduction of current signals. The differential current signals were directly proportional to the logarithm of the concentration of DNase I in the range of 10 À5 units per mL to 0.5 units per mL with a detection limit of 10 À6 units per mL (S/N ¼ 3). The sensor exhibits a wide linear range and superior sensitivity and can be applied in more bioanalytical systems.

An electricity-fluorescence double-checking biosensor based on graphene for detection of binding kinetics of DNA hybridization

“…The honeycomb like structure of graphene oxide (GO) facilitates its combination with single stranded DNA through p-p stacking. 16,17 The zero-band gap structure of GO makes it an effective uorescence quencher in FRET sensors. This unique ssDNA-GO interaction has been used in developing biosensors for DNA, proteins, and small molecules by uorescence method.…”

Human Cyclophilin B Nuclease Activity Revealed via Nucleic Acid‐Based Electrochemical Sensors

“…In NBEs, electron transfer can be measured between the redox reporter and the electrode surface via square wave voltammetry (Figure 1A, bottom). The platform can be used to study nucleic acid hydrolysis via continuous monitoring of the reporter's voltametric signal following protein additions [19, 20] . The idea is that if CypB can hydrolyze nucleic acids, addition of this protein to solutions where NBEs are immersed should result in cleavage of the electrode‐bound oligos (Figure 1B, top), releasing the reporter‐modified strands to the bulk solution where they get infinitely diluted and cannot be detected.…”

Zinc Oxide Tetrapods Based Biohybrid Interface for Voltammetric Sensing ofHelicobacter pylori

“…This is due to the formation of the maximum immunocomplex on the interface at lower acidic or alkaline surroundings. 52 Figure 6B shows the effect of temperature on the immunosensor, which is carried out in sodium phosphate buffer and electrolytic solution containing 0.2 ng/mL CagA antibody. The electrolytic solution is kept at various temperatures ranging from 10 °C to 50 °C at an interval of 5 °C.…”

“…However, 7.5 pH was selected as the optimum pH value for H. pylori detection as it gave the lowest oxidation and reduction peaks among all the pH values. This is due to the formation of the maximum immunocomplex on the interface at lower acidic or alkaline surroundings …”