Synthesis of Isolated DNA Aptamer and Its Application of AC-Electrothermal Flow-Based Rapid Biosensor for the Detection of Dengue Virus in a Spiked Sample

Abstract

Dengue fever is an infectious disease caused by the dengue virus (DENV) and is transmitted by mosquitoes in tropical and subtropical regions. The early detection method at a low cost is essential. To address this, we synthesized the isolated DENV aptamer for fabricating a rapid electrochemical biosensor on a Au interdigitated microgap electrode (AuIMGE). The DENV aptamers were generated using the SELEX (systemic evolution of ligands by exponential enrichment) method for binding to DENV surface envelope proteins. To reduce the manufacturing cost, unnecessary nucleotide sequences were excluded from the isolation process of the DENV aptamer. To reduce the detection time, the alternating current electrothermal flow (ACEF) technique was applied to the fabricated biosensor, which can shorten the detection time to 10 min. The performance of the biosensor was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the diluted DENV protein solution, the linear range of the concentrations was from 1 pM to 1 μM and the LOD was 76.7 fM. Moreover, the proposed biosensor detected DENV in a diluted spiked sample at a linear range of 10 −6 to 10 6 TCID 50 /mL, while the detection performance was proven with an LOD of 1.74 × 10 −7 TCID 50/ mL along with high selectivity.

Rapid detection of carcinoembryonic antigen by means of an electrochemical aptasensor

“…Then, the semicircle steadily increased when CEA aptamer (6) was immobilized at concertation of 5 μM ( R ct = 1716 Ω) as the result of the redox buffer’s negative electroactive ions rejecting the negatively charged phosphate groups of the DNA aptamer, confirming its attachment to the surface, 32 , 33 , 34 which is consistent with the CV data, where the cathode peak and anode peak decreased after fixing the aptamer because the negatively charged phosphoric acid backbones of aptamer impede the electron transfer of the redox couple. 27 , 35 Further blocking with MCH solution resulted in the charge transfer resistance change ( R ct = 5333 Ω), following CV peak currents decrease because MCH could form an additional barrier on the surface of the IDE and confirm the filling of free surface on the IDE surface. Finally, the R ct increased to 19,457 Ω, when incubated with a 2 ng/mL CEA target protein for 20 min.…”