Impedimetric DNA biosensor based on a nanoporous alumina membrane for the detection of the specific oligonucleotide sequence of dengue virus

Abstract

A novel and integrated membrane sensing platform for DNA detection is developed based on an anodic aluminum oxide (AAO) membrane. Platinum electrodes (~50-100 nm thick) are coated directly on both sides of the alumina membrane to eliminate the solution resistance outside the nanopores. The electrochemical impedance technique is employed to monitor the impedance changes within the nanopores upon DNA binding. Pore resistance (Rp) linearly increases in response towards the increasing concentration of the target DNA in the range of 1 × 10⁻¹² to 1 × 10⁻⁶ M. Moreover, the biosensor selectively differentiates the complementary sequence from single base mismatched (MM-1) strands and non-complementary strands. This study reveals a simple, selective and sensitive method to fabricate a label-free DNA biosensor.

Figure 1.

(a) Scheme of DNA immobilization procedure; (b) Schematics of nanoporous alumina membrane for impedimetric biosensing of DNA target; (c) The equivalent circuit model for fitting the impedimetric experimental data.

Figure 2.

Differential pulse voltammetry current signal response of the integrated nanoporous membrane sensor toward increasing concentration of complementary DNA target from 10⁻¹² to10⁻⁶ M.

Figure 3.

Nyquist plots of (a) integrated nanoporous membrane electrode grafted with DNA probe, (b) unmodified nanoporous membrane electrode in response toward increasing concentrations of target DNA (10⁻¹²∼10⁻⁶ M), (c) 200 nm pore size membrane sensor grafted with DNA probe toward increasing concentration of DNA targets (10⁻¹⁰∼10⁻⁶ M).

Figure 4.

Calibration plot of pore resistance against the logarithm of complementary target DNA concentration.

Figure 5.

(a) Nyquist plots of ssDNA probe grafted nanoporous alumina membrane after exposure to noncomplementary target sequence (MM-21), single base mismatched target sequence (MM-1) and complementary target sequence. Each measurement step was followed by a denaturing step; (b) Bar chart illustrating the R_p values obtained from the impedance responses of the integrated nanoporous membrane sensor after consecutive steps of incubation with DNA targets followed by a regeneration step; (c) Nyquist plots of unmodified nanoporous alumina membrane in response to noncomplementary target sequence (MM-21), single base mismatched target sequence (MM-1) and complementary target sequence, following the same procedure and order as (a).