Chip‐based detection system for the on‐site analysis of animal diseases

Abstract

A portable and robust system which is suitable for the automated analysis of DNA or RNA of selected pathogens such as foot‐and‐mouth disease virus (FMDV) is developed. The system incorporates a stationary PCR chip and is coupled with a DNA chip and an electrical detection for the sequence‐specific identification of the PCR products. The PCR chip represents a miniaturized form of the classical thermocyclers and enables a fast and sensitive amplification as well as labeling of specific DNA sequences with minimal space and energy requirements. The detection and identification of the PCR products is performed on a DNA chip with an electrical detection scheme. The combination of the two technologies allows a very fast and highly specific sequence‐based detection and differentiation of pathogens. Further, it combines the accuracy of sequence analysis with the speed of chip technologies. For the total analysis including DNA amplification and DNA detection, less than 2 h are required.

Easy Daylight Fabricated Hydrogel Array for Colorimetric DNA Analysis

“…The detection of biotin‐labeled oligonucleotides in the hydrogel was realized by silver nanoparticle deposition . A blocking step was performed with 1 M glycine buffer for 15 min at room temperature to minimize the unspecific binding of the streptavidin–horseradish‐peroxidase‐conjugate.…”

“…The deposition of silver nanoparticles within the hydrogel was analyzed by gray value scaling (Program Image J) …”

“…The bleaching of fluorescent dyes under light exposure requires a light‐protected workflow as well as sample storage. In recent years, the improvement of DNA detection assays for on‐site or near‐patient testing of viral or bacterial pathogens led to the development of convenient read‐out regimes, which were based on metallic nanoparticles . One step in this direction was realized by combining hydrogels and colorimetric signal detection .…”

“…Here, the presence of target DNA on the surface of the hydrogel was traceable by naked eye due to a color change from transparent to red (gold nanoparticles) or even black (silver nanoparticles). Silver nanoparticles as an endpoint DNA‐detection tool were also successfully used in a 2D chip platform for the analysis of animal or plant pathogens . The aim of the present study was the creation of an alternative method for naked eye DNA detection utilizing the whole volume of the hydrogels for maximum signal output.…”

Towards on-site testing of Phytophthora species

“…The Ypt1 region was chosen to design the species-specific capture probes 41 (Figure 1). These capture probes (Eurofins MWG Operon, Ebersberg, Germany; Table 1 The specific detection of Phytophthora species was performed in a microfluidic device as previously described 41,46,47 . 20 µl of the HDA products were dissolved in 50 µl buffer (5 × SSC/0.1 % SDS) and applied on the chips for 15 min at 58 °C using an interval flow and further processed.…”