A paralleled readout system for an electrical DNA-hybridization assay based on a microstructured electrode array

Abstract

DNA analytics is a growing field based on the increasing knowledge about the genome with special implications for the understanding of molecular bases for diseases. Driven by the need for cost-effective and high-throughput methods for molecular detection, DNA chips are an interesting alternative to more traditional analytical methods in this field. The standard readout principle for DNA chips is fluorescence based. Fluorescence is highly sensitive and broadly established, but shows limitations regarding quantification ͑due to signal and/or dye instability͒ and the need for sophisticated ͑and therefore high-cost͒ equipment. This article introduces a readout system for an alternative detection scheme based on electrical detection of nanoparticle-labeled DNA. If labeled DNA is present in the analyte solution, it will bind on complementary capture DNA immobilized in a microelectrode gap. A subsequent metal enhancement step leads to a deposition of conductive material on the nanoparticles, and finally an electrical contact between the electrodes. This detection scheme offers the potential for a simple ͑low-cost as well as robust͒ and highly miniaturizable method, which could be well-suited for point-of-care applications in the context of lab-on-a-chip technologies. The demonstrated apparatus allows a parallel readout of an entire array of microstructured measurement sites. The readout is combined with data-processing by an embedded personal computer, resulting in an autonomous instrument that measures and presents the results. The design and realization of such a system is described, and first measurements are presented.

Integrated Nanoparticle–Biomolecule Hybrid Systems: Synthesis, Properties, and Applications

“…[230] The immobilization of nanoparticles on surfaces may also be used to yield high-surface-area electrodes [231] and hence to increase the hybridization capacity of the surface. [232] Such use of NP supporting films relied on the self-assembly of 16-nmdiameter Au NPs on a cystamine-modified gold electrode and resulted in surface densities of oligonucleotides as high as 4 10 14 molecules per cm À2 .…”

Current strategies for electrochemical detection of DNA with solid electrodes

“…The authors claim a selectivity factor of ~10 9 :1. Fritzsche has automated Mirkin's strategy [124] by design of an autonomous instrument. The system consists of a chip containing 42 electrode gaps integrated, via a multiplexed ohmmeter, with a readout system that includes data processing.…”

“…Enough sensitivity to avoid PCR preamplification has been achieved by use of enzymatic labels [78], impedance measurements [113,115,116], and metal tags in combination with resistance measurements [122,123,124]. Although in some applications (genotyping, pathogen identification etc.)…”

Novel Bottom‐Up SERS Substrates for Quantitative and Parallelized Analytics

“…After an incubation period of five minutes the reaction is stopped by rinsing with water, and the electric conductivity is determined with a purpose-built measurement instrument. [21] The examination of the deposited particles using AFM and SEM at different particle densities shows in all images the above-mentioned special structure of the EGNPs (see Figure 1). Especially at higher particle densities, the sharp and rough structure of the particles becomes clear.…”