Modification of an automated liquid-handling system for reagent-jet, nanoliter-level dispensing

Reducing the scale of biochemical reactions is becoming commonplace. Exampl es include the screening of large libraries of chemical compounds or gene s equences. These applications demand the ability to transfer sub-microliter volumes of fluid. To this end, we have modified a Hamilton(R) MICROLAB(R) 2 200 with high-speed solenoids and a liquid pressurization system to modulat e volume delivery down to the nanoliter level. Additional modifications inc lude the use of sapphire-tipped dispensing nozzles and a high-resolution su bstage to assist in the construction of DNA microarrays. Techniques for cha racterizing the dispensed volume are presented.