Why a Special Issue on Acoustic Liquid Handling?

Certain topics stir excitement in the hearts and minds of scientists. Synthesizing new genes with never before seen capabilities, discovering cures for Ebola and other devastating diseases, devising new breakthrough drug therapy for cancer sufferers, expanding the understanding of protein structure via crystallography—those are topics that thrill and motivate. By comparison, liquid handling may appear prosaic. Whether it is a hose, a pipette, an eye-dropper, pistonor peristaltic-driven systems, or an ink-jet printer, there is a “been there, done that” attitude. It seems as though everything that could be said about a liquid handler has already been said many times over. So why, then, are we devoting an entire issue of the Journal of Laboratory Automation to one specific type of liquid handling—acoustic droplet ejection (ADE)? Precisely because ADE, a relative newcomer to liquid handling, enables new, far-reaching science. Experiments that were impossible for practical reasons become simple and easy. The ability to use sound waves to move liquids in precise nanoliter increments has wide-sweeping effects on driving exciting advances in science, including those topics mentioned above. ADE fundamentally changes what can be done, and it has facilitated breakthroughs in new areas of innovative research. ADE is not another evolutionary step in the lab. It is correctly described as truly revolutionary. The importance of control and precision with increasingly lower transfer volumes has become elevated as detection technologies have significantly improved, making miniaturization to highdensity formats not only possible but also desirable for both throughput and financial reasons. Already broadly employed in drug discovery, ADE is now becoming an essential part of many labs. Synthetic biology? Cures for emerging diseases? New therapies for cancer? All of these have exploited the advantages of ADE. Kanigowska et al. use ADE to generate new genes at radically lower costs. Their process would have been financially unfeasible were it not for ADE. This reduction in expenses echoes the drug discovery efforts reported by Wingfield et al. Rasmussen et al. use assay-ready plates made via ADE to test drugs against Ebola and other BSL-4 pathogens and open up faster, simpler ways to collaborate to end these scourges. Advances in individualized medicine that identify exactly what drugs or combinations of drugs are the best anticancer therapy for any specific individual are covered by Blom et al. and Kulesskiy et al. The miniaturization and speed provided by ADE move individualized systems medicine from theory to reality. Ericson et al. and Wu et al. use ADE to expand protein crystallography via miniaturization and crystallization with multiple ligands. Of great interest to attendees of SLAS2015, the SLAS International Conference and Exhibition in Washington, D.C., as well as to all people interested in faster high-throughput assays is the article describing the first ever acoustic interface to a mass spectrometer. In “Novel Acoustic Loading of a Mass Spectrometer: Toward Next-Generation High-Throughput MS Screening,” Sinclair et al. elaborate upon the 2015 SLAS Innovation Award–winning presentation on the coupling of mass spectrometry with ADE to analyze as many as three assays per second. In a related article, Chin et al. show how they combine ADE with matrix-assisted laser desorption/ ionization mass spectrometry (MALDI MS). As mentioned, ADE is used extensively in drug discovery. In this issue, Naylor et al. expand the use of ADE in compound management to show how it preserves the potency of peptides. Edwards et al. describe ADE-enabled high-throughput epigenetic methyltransferase assays. Acoustic droplet ejection is fundamentally different from earlier technologies. It uses focused sound to propel droplets of liquids upward from a source location to a destination. The roots of ADE go back a century, when Wood and Loomis used acoustic energy to propel droplets of liquid from a vessel. With modern ADE, a low level of sound energy is focused at the meniscus, causing a mound to form on the surface of the liquid. When a small additional amount of energy is put into the liquid, droplets are propelled upward to an inverted target or microtiter plate with unparalleled precision and accuracy. Most important for achieving high scientific impact, ADE is a completely touchless transfer method. Traditionally, the term noncontact transfer has meant that the device transferring 619712 JLAXXX10.1177/2211068215619712Journal of Laboratory AutomationOlechno et al. research-article2015