Investigation of microfabrication of biological sample arrays using piezoelectric and bubble-jet printing technologies

Modified commercial ink-jet printers are simple and cost-effective tools for the fabrication of microarrays containing biological samples. In this paper, the two most common ink-dispensing technologies, thermal and piezoelectric, were investigated, tested, and compared in terms of their ease of use and spotting quality. Ink cartridges were used as sample reservoirs and refilled with small volumes (as low as 20 (mu)L) of water-based sample solutions containing herring sperm DNA and fluorescent dyes. Different solution compositions were evaluated and compared. Microscopic spots (<200 (mu)m) were printed on various membranes (cellulose, nylon, nitrocellulose, and Zeta-Probe) and glass microscope slides. This technique enabled rapid preparation of a large number of printed arrays of biological materials at extremely low cost. To further demonstrate the utility of the microarray platform, we performed an assay of Bacillus anthracis, detected through DNA hybridization using fluorescent probes complementary to the B. anthracis target printed on a membrane. A comparison of Zeta-Probe and nylon membranes yielded less nonspecific binding when using the Zeta-Probe membrane. In addition, detection of 100 fmol of the target per printed spot was demonstrated.