Researchers interested in printing their own microarrays in-house now have an array of options — from contact (pin or split pin) and non-contact printing methods (bubblejet or piezoelectric inkjet) to in situ array synthesis.

Bio-Rad Laboratories of Hercules, California, launched the BioOdyssey Calligrapher miniarrayer last month, which prints oligos, proteins or cell lysates onto slides, membranes or 96-well plates. This bench-top instrument has an eight-pin print head and prints up to 16 slides at a time. Optional extras include humidity and temperature controls. Telechem International of Sunnyvale, California, has also added humidity controls to its NanoPrint microarrayer.

A plate-arraying option is now available on the BioRobotics MicroGrid ii and GeneMachines OmniGrid Accent platforms from Genomics Solutions of Holliston, Massachusetts. This enables DNA and protein microarrays of up to 1,000 features per well to be printed in 96- and 384-well microplates, providing high-throughput, multiplexing capabilities for diagnostic, ELISA and protein–protein interaction applications.

Arrayjet makes non-contact printing high-throughput. Credit: ARRAYJET

Non-contact printers may have got a bad rap in the early days but Arrayjet of Mayfield, UK, hopes to win over researchers with its new Aj120 piezoelectric inkjet printer, which it launched in July. “Contact printing can affect the quality of the data you get because it introduces surface-based artefacts into the microarray,” says Duncan Hall, sales and marketing director for Arrayjet. Pin printers can also be very susceptible to atmospheric conditions, he says, particularly when hygroscopic printing buffers are used. “We carry our sample inside the print head so there isn't any evaporation from the print head.”

The Aj120 includes a microplate stacker and lid lifter, which enables walk-away printing of microarrays from up to 48 (96- or 384-well) microtitre plates. With the standard 12-sample connector block, 100 slides (samples and replicates side-by-side) can be printed in 90 seconds, says Hall. Additional replicates can be printed on the fly in no extra time. The Aj120 prints DNA, proteins and intact cells with a 100-µm spot diameter. PerkinElmer Life and Analytical Sciences of Boston, Massachusetts, also offers contact and piezoelectric non-contact systems.

For those with deeper pockets, CombiMatrix sells a CustomArray desktop DNA synthesizer for the in situ synthesis of oligonucleotides on microarrays with up to 12,000 features. Synthesis occurs on a blank CombiMatrix semiconductor chip using standard phosphoramidite chemistry methods.

D.G.