DNA diagnostics: nanotechnology-enhanced electrochemical detection of nucleic acids

Abstract

The detection of mismatched base pairs in DNA plays a crucial role in the diagnosis of genetic-related diseases and conditions, especially for early stage treatment. Among the various biosensors that have been used for DNA detection, EC sensors show great promise because they are capable of precise DNA recognition and efficient signal transduction. Advancements in micro- and nanotechnologies, specifically fabrication techniques and new nanomaterials, have enabled for the development of highly sensitive, highly specific sensors making them attractive for the detection of small sequence variations. Furthermore, the integration of sensors with sample preparation and fluidic processes enables for rapid, multiplexed DNA detection essential for POC clinical diagnostics.

Figure 1

Schematic illustration demonstrating the integration of nanomaterials and micro/nanofabrication technologies for constructing electrochemical DNA sensors.

Figure 2

Common nanomaterials utilized in electrochemical biosensors for DNA/RNA diagnostics; (A) nanomaterials for electrode coatings, (B) nanomaterials for probe labeling, (C) nanomaterials for target labeling and (D) nanomaterials for signal reporter. Adapted and rearranged from reference. Reprinted from Xu K et al. 2009 Sensors 9:5534–5557. Copyright ©.2009 by authors, with permission.

Figure 3

Schematic illustrating the principles for electrochemical DNA sensors. (A) Direct oxidation/reduction of nucleotide bases. (B) Detection of intercalating complex for single/duplex stands. (C) Detection of specific DNA with labeled reporting molecules. (D) Detection of specific DNA with integrated capture probe and reporter probe. (E) Direct detection after specific DNA enzymatic process. (F) Detection of extra labeled reporter after specific DNA enzymatic process.

Figure 4

Schematic illustration depicting the various electrical field effects during DNA recognition, including (A) orientation changes, (B) conformational changes, (C) separation from interferents, (D) accumulation to local domain, (E) hybridization with complementary sequence and (F) denaturation of non-specific sequence.

Figure 5

Images of nanomaterials and nanoelements utilized for electrochemical sensors. (A) Transmission electron microscopy (TEM) image of a CdTe-Au multi-segment nanowire. Reprinted from Wang X et al. 2008 Nano Lett 8:398–404: copyright © 2008 American Chemical Society, with permission.. (B) Scanning electron microscopy (SEM) image of patterned silicon nanowires, which are individually addressable by oxide-passivated metal contact lines. Reprinted from Chua JH et al. 2009 Anal Chem 81:6266–6271; copyright © 2009 American Chemical Society, with permission. (C) Atomic force microscopy (AFM) image of probe ssDNA immobilized inside an oriented nanowell (ONW) array. Reprinted from Lee H et al. 2006 Appl Phys Lett 89:113901; Copyright © 2006 American Institute of Physics, with permission. (D, E) SEM images of multi-walled carbon nanotube (MWCNT) arrays patterned using UV lithography and e-beam lithography respectively. Reprinted from Li J et al. 2003 Nano Lett 3:597–602; Copyright © 2003 American Chemical Society, with permission. (F) SEM image of a CNT-poly-l-lysine film on top of a carbon paste electrode. Adapted and rearranged from references. Reprinted from Jiang C et al. 2008 Electrochim Acta 53:2917–2924; Copyright © 2007 Elsevier Ltd., with permission.