Oxygen vacancy modulated MnO2 bi-electrode system for attomole-level pathogen nucleic acid sequence detection

Abstract

Fabricated an inexpensive bi-electrode electrochemical sensor for nucleic acid amplification detection with a user-friendly interface in a short detection time.Electronic conduction of the metal oxide sensing layer was successfully optimised by manipulating the concentration of oxygen vacancies.The sensing layer was annealed at various temperatures and optimised by testing their electrical, optical, and chemical properties.The fabricated device was able to detect dengue virus sequence DNA and Staphylococcus aureus genomic DNA with clinically relevant limit of detection.

A batch processed titanium–vanadium oxide nanocomposite based solid-state electrochemical sensor for zeptomolar nucleic acid detection

“…1a. 43 An advantage of using the proposed DEES in comparison to commercial SPEs is that the DEES can be batch processed whereas for every test sample to be evaluated a separate SPE unit would be needed. Therefore, a bundle of SPEs would be required to perform any series measurements or to have a statistical dataset for any nucleic acid amplification.…”

“…The generation of the PDMS electrolyte holding cavities was performed as described in our previous work. 43 Briefly, a thin, transparent, and flexible layer of PDMS was integrated onto the electrode that functions as an electrolyte holding cavity. The cavity serves the bi-fold purpose of providing a uniform contact area for every measurement and preventing evaporation during the testing of the samples.…”

Titanium-vanadium oxide nanocomposite based solid-state dual-electrode sensor for SARS-CoV-2 nucleic acid detection

“…Next, the electroanalytical response of the proposed 20%-TVO electrode was compared with that of our previously reported MnO2 bi-electrode system 35 . As mentioned earlier, the lower IEP (1.5 -2.3 43 ) of the TVO layer should attract more positively charged MB from the electrolyte (pH 7.5 for buffer and pH 8.8 for amplification) compared to the MnO2 system (IEP 4 -5 37 ).…”

“…We have recently investigated the end-point detection of pathogen nucleic acid with electrochemical NAATs utilizing an oxygen-vacancy modulated MnO2 electrode in a two-electrode electrochemical device 35 . Contrary to traditional three-electrode geometry, a 2-electrode device geometry with a working and pseudo-or quasi-reference counter electrode (QRCE) has the following advantages, (i) simplification of the sensor structure, (ii) lowering of the ohmic resistance effect, (iii) elimination of liquid junction potential, and (iv) avoids contamination of the target solution by the solvent molecules (or ions) of a conventional reference electrode 36 .…”

“…Contrary to traditional three-electrode geometry, a 2-electrode device geometry with a working and pseudo-or quasi-reference counter electrode (QRCE) has the following advantages, (i) simplification of the sensor structure, (ii) lowering of the ohmic resistance effect, (iii) elimination of liquid junction potential, and (iv) avoids contamination of the target solution by the solvent molecules (or ions) of a conventional reference electrode 36 . By analyzing I-V characteristics and using methylene blue (MB) as the redox mediator 35 , the electrode successfully detected electrochemical RCA (using a pre-synthesized circular DNA as the template and a dengue virus sequence-bearing primer as target) and polymerase chain reaction (PCR, using Staphylococcus aureus vraR gene as target) with LODs in the order of 10 3 copies. However, the work utilizes already purified genomic DNA or synthetic DNA as the target.…”