Electrical Detection of Viral DNA Using Ultramicroelectrode Arrays

Abstract

A fully electrical array for voltammetric detection of redox molecules produced by enzyme-labeled affinity binding complexes is shown. The electronic detection is based on ultramicroelectrode arrays manufactured in silicon technology. The 200-microm circular array positions have 800-nm-wide interdigitated gold ultramicroelectrodes embedded in silicon dioxide. Immobilization of oligonucleotide capture probes onto the gold electrodes surfaces is accomplished via thiol-gold self-assembling. Spatial separation of probes at different array positions is controlled by polymeric rings around each array position. The affinity bound complexes are labeled with alkaline phosphatase, which converts the electrochemically inactive substrate 4-aminophenyl phosphate into the active 4-hydroxyaniline (HA). The nanoscaled electrodes are used to perform a sensitive detection of enzyme activity by signal enhancing redox recycling of HA resulting in local and position-specific current signals. Multiplexing and serial readout is realized using a CMOS ASIC module and a computer-controlled multichannel potentiostat. The principle of the silicon-based electrical biochip array is shown for different experimental setups and for the detection of virus DNA in real unpurified multiplex PCR samples. The fast and quantitative electronic multicomponent analysis for all kinds of affinity assays is robust and particle tolerant.

Development of Interdigitated Array Electrodes with Surface-enhanced Raman Scattering Functionality

“…Among various microelectrodes and their arrays, interdigitated array electrodes (IDAEs) are well recognized among analytical scientists [1][2][3][4][5] and have been exploited in several applications such as detectors for lab-on-a-chip systems, [6][7][8][9][10] scanning electrochemical microscopes (SECM), 11 quantitative trace analyzers of redox species, 12 nanoparticle detection devices, 13 analytical and bioanalytical sensors and others due to their high current amplification characteristics achieved by redox cycling or feedback effects. [14][15][16] However, electrochemical methods are not fruitful for analyzing the mixtures of electroactive species because of the additive diffusion fluxes of the components.…”

Redox cycling in nanofluidic channels using interdigitated electrodes

“…They are primarily employed as conductometric [29][30][31] and amperometric sensors. As amperometric sensors, they are often used in the detection of biomolecules [32][33][34] and have even been employed as detectors in capillary electrophoresis [8,35,36]. A sketch of an IDE is shown in Fig.…”

Redox Cycling Effect on the Surface-enhanced Raman Scattering Signal of Crystal Violet Molecules at Nanostructured Interdigitated Array Electrodes

“…4 The miniaturized sizes of these devices have been exploited in many applications, such as lab-on-a-chip systems, [5][6][7][8][9] a scanning electrochemical microscope (SECM), 10 analysis in a single biological cell 11 and so on. The interdigitated array (IDA) electrode involves one of the most effective structures to improve the sensitivity in detecting electroactive species through a redox cycling mechanism.…”