Development and characterization of a disposable plastic microarray printhead.

During the last decade microarrays have become a powerful analytical tool. Commonly microarrays are produced in a non-contact manner using silicone printheads. However, silicone printheads are expensive and not able to be used as a disposable. Here, we show the development and functional characterization of 8-channel plastic microarray printheads that overcome both disadvantages of their conventional silicone counterparts. A combination of injection-molding and laser processing allows us to produce a high quantity of cheap, customizable and disposable microarray printheads. The use of plastics (e.g., polystyrene) minimizes the need for surface modifications required previously for proper printing results. Time-consuming regeneration processes, cleaning procedures and contaminations caused by residual samples are avoided. The utilization of plastic printheads for viscous liquids, such as cell suspensions or whole blood, is possible. Furthermore, functional parts within the plastic printhead (e.g., particle filters) can be included. Our printhead is compatible with commercially available TopSpot devices but provides additional economic and technical benefits as compared to conventional TopSpot printheads, while fulfilling all requirements demanded on the latter. All in all, this work describes how the field of traditional microarray spotting can be extended significantly by low cost plastic printheads.

DNA microarray for detection of antibiotic resistance determinants in Bacillus anthracis and closely related Bacillus cereus.

We developed a multiplex PCR for amplification of ten genes involved in resistance to ciprofloxacin, doxycycline, rifampin, and vancomycin in Bacillus anthracis and closely related Bacillus cereus. Enzymatic labelling of PCR products followed by hybridization to oligonucleotide probes on a DNA microarray enabled simultaneous detection of resistance genes tetK, tetL, tetM, tetO, vanA, and vanB and resistance-mediating point mutations in genes gyrA, gyrB, parC, and rpoB. The presented assay allows detection of clinically relevant antibiotic resistance determinants within 4h and can be used as a time-saving tool supporting conventional culture-based diagnostics.